Which aluminum alloy best for bending? Using thin sheet.

Dan Miller · Jun 9, 2013

Using the thickness I wish to work with, which will be .025", which aluminum alloy will bend 90* and stay bent with little springback? The following alloys are all available in my chosen thickness of sheet stock.

2024 - T3

5052 - H32

6061 - T6

My parts will be stamped to roughly 1/2" X 3/4" and then formed in a series of stations. There will be four 90* bends. Just asking advice on which alloy will bend well, crack the least and when bent, stay that way with minimal springback. To give an idea of the shape of the part, imagine a small, square tunnel, when the part is placed on a flat surface.

Thanks in advance for any suggestions.

Dan Miller

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littlemachinist · Jun 9, 2013

Dan Miller said:
Using the thickness I wish to work with, which will be .025", which aluminum alloy will bend 90* and stay bent with little springback? The following alloys are all available in my chosen thickness of sheet stock.

2024 - T3

5052 - H32

6061 - T6

My parts will be stamped to roughly 1/2" X 3/4" and then formed in a series of stations. There will be four 90* bends. Just asking advice on which alloy will bend well, crack the least and when bent, stay that way with minimal springback. To give an idea of the shape of the part, imagine a small, square tunnel, when the part is placed on a flat surface.

Thanks in advance for any suggestions.

Dan Miller

.

I would go with the 6061 - T6. It has proven to work well.

robert123 · Jun 9, 2013

5052-H32 can be bent with the tightest radius of the three (least likely to crack with a smaller bend radius). All will have some springback. I don't know if one is better than the others in that regard. I would just experiment and adjust your bend as needed. If you get 1 degree springback, make your bends 89 degrees so the end result is 90.

smdubovsky · Jun 9, 2013

Not 6061 (especially in T6). Easily cracks if bent along the 'grain'. Across the grain can work ok, but one of the other alloys is probably a far better choice.

behindpropellers · Jun 9, 2013

Is strength a factor? 3003 could be used.

I would not go with 2024 or 6061 T6 since it would crack.

5052 out of your list is the best bet. If you don't need the strength then I would look into 3003 also.

Tim

Ray Behner · Jun 9, 2013

behindpropellers said:
Is strength a factor? 3003 could be used.

I would not go with 2024 or 6061 T6 since it would crack.

5052 out of your list is the best bet. If you don't need the strength then I would look into 3003 also.

Tim

Without a doubt!

metlmunchr · Jun 9, 2013

I'd look at 3003-H14 as well unless you need the additional strength of 5052. In the H14 temper, .062 stock can take a dead sharp (zero inside radius) bend without cracking. Its one of the most widely available aluminum alloys and is likely cheaper than 5052 as well.

From hands on experience, 6061-T6 will crack, and 2024-T3 will break like a piece of glass.

swarf_rat · Jun 9, 2013

Since every aluminum alloy has about the same Youngs Modulus, the spring back is a direct tradeoff with strength: Higher yield point = more spring back.

dlaw · Jun 9, 2013

If you ever want to weld your product do not use 2024. It is not considered weldable. 5052 & 3003 weld fine.

Dan Miller · Jun 9, 2013

Thanks very much for all your answers.

Looking at specs on the two most promising alloys, seems like 3003-H14 is very soft and almost gummy when drilled, etc. The alloy 5052-H32 may bend well enough for my use and shows about 50% higher tensile and yield.

I will test both and go with whichever seems best for my use.

.

metlmunchr · Jun 10, 2013

Dan Miller said:
Looking at specs on the two most promising alloys, seems like 3003-H14 is very soft and almost gummy when drilled, etc. The alloy 5052-H32 may bend well enough for my use and shows about 50% higher tensile and yield.

3003 definitely isn't fun for drilling or any other sort of operation involving edge cutting tools. As a general rule, the machinability of any aluminum alloy is inversely proportional to its formability. For any sort of volume production, punching is the only way to easily maintain good quality holes in any of the highly formable alloys, and this is particularly true with thin sheet stock.

welderjosh · Jun 10, 2013

We have done a bunch of tests and 6061-T6 will handle a minimum ISR of 2.5x the material thickness. Any tighter and it cracks, but if you stay bigger then no problem. We have built hundreds of military parts up to 0.125" thick with this as a rule.

E.F. Thumann · Jun 10, 2013

My shop does between 75-120k bends in 3003 .032" each year. You didn't mention what machine you will be putting the tooling in. Is it a proper press brake? OBI? homemade? With thin material, exact/repetitive bottom-of-stroke position is the only way to maintain accuracy if you are air bending with spring back. If you have a less-than-ideal machine(or even if you don't), consider coining the bends. It's repeatable/reliable, and easy with thin aluminum.

Dan Miller · Jun 11, 2013

E.F. Thumann,

I will be using an OBI press that is in good condition. The idea is to have a line of forming stations lined up in a two post die set. I will move the parts from station to station. It is not worth making a progressive die for this job as the quantity of parts is only 3 - 4K per year. Also I wish to stay versatile and switch out one, or maybe two of the stations, for slight variations in configuration.

Your idea of coining the part makes sense. Some years ago I made a coining die for copper and the part came out just as intended. Coining can be controlled in a punch press with good repeatable results. Thanks for the idea.

I will play with 3003 to start and will also go up the strength ladder by testing 5052 next.

Dan Miller

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E.F. Thumann · Jun 11, 2013

Dan, you sound like you are well on your way. Remember that coining is an area beyond air bending, i.e. the part is bent 90, past 90, the punch penetrates the face of the material, plastically deforms it, and "coins" it back to 90. When you are putting your die set together , make sure you incorporate bolster/shim blocks underneath the actual die former, that way you can shim the bolsters up until you creep up on 90, then approx. 92deg (shouldn't go much beyond 92 if you are using 90deg punch/die combo for this), once you hit 92ish, continue to shim, my guess would be coining would be approx. .004-.006 beyond). A last thought is to incorporate a urethane pad in the die set, to get the tonnage to coin the part, but avoid being so close to the actual bottom of stroke of the press, i.e. risking bottoming/tonnage-spiking/lockups. Good luck in your endeavor.

slugger · Jun 11, 2013

E.F. Thumann said:
Dan, you sound like you are well on your way. Remember that coining is an area beyond air bending, i.e. the part is bent 90, past 90, the punch penetrates the face of the material, plastically deforms it, and "coins" it back to 90. When you are putting your die set together , make sure you incorporate bolster/shim blocks underneath the actual die former, that way you can shim the bolsters up until you creep up on 90, then approx. 92deg (shouldn't go much beyond 92 if you are using 90deg punch/die combo for this), once you hit 92ish, continue to shim, my guess would be coining would be approx. .004-.006 beyond). A last thought is to incorporate a urethane pad in the die set, to get the tonnage to coin the part, but avoid being so close to the actual bottom of stroke of the press, i.e. risking bottoming/tonnage-spiking/lockups. Good luck in your endeavor.

I have bent a lot of 2024-H3 and it cracks easily and has to be 'snuck up on'. Not good for production. I would use 5000 series. I wouldn't use 3003 in anything but tubing where low strength and tight bends are required.

gilbertjames332 · Jun 8, 2016

If you could actually tell us a bit more about what kind f characteristics you require other than bending, we can help you better

Aluminium alloys with more of aluminium have little structural value but are ductile and some of the alloys have good corrosion resistance. Check out http://www.jindalaluminium.com/ for 6061 if you are interested, it is one of their most popular alloys.

Bobw · Jun 8, 2016

Here is a strip of .030 (or was it .032) thick 3003 that I was making some parts out of a while back..
That was done in about 20 seconds with just my fingers.. Not exactly the strongest stuff going..

MrSteve · Jun 8, 2016

Absolutely 5052-H32 for bending, unless you can tolerate *huge*bend radii (lest it crack), then 6061 or 2024 may be okay.

5052 & 3003 are the common alloys for sheet metal bending and forming.

mort210 · Jun 8, 2016

2024-T3 is used like crazy for sheet metal parts in aerospace. Probably by far the most common... Just follow proper bend radii tables and it should be fine. If you can, give 6013 a try. Buy in untreated condition, cold work, than age to strengthen. Awesome alloy.

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